Fabrication of molybdenum carbide and hafnium carbide field emitter arrays

Abstract

We report on a process for the fabrication of Mo2C and HfC refractory metal carbide field emitter arrays using a modified Spindt tip fabrication process. Measurements of the aspect ratios of emitter cones showed that Mo2C tip structures have an aspect ratio similar to Mo field emitter tips. Where as with HfC, tip structures with a higher aspect ratio than either Mo or Mo2C were obtained. The measured aspect ratios for Mo, Mo2C, and HfC tips were 1.09, 1.10, and 1.20, respectively. While the target materials to fabricate the arrays were the appropriate carbides, x-ray photoelectron spectroscopy of the carbide films showed evidence for the presence of significant amount of oxygen throughout the films, mostly in the form of oxycarbides. The primary purpose of this report is to describe materials and processes suitable for large area field emission display applications. However, we also provide preliminary electrical results which demonstrate the feasibility of fabrication of metal carbide field emitters and identify important details to be addressed to achieve successful electrical performance.